The present invention relates to in-vehicle navigation systems and more particularly, the present invention relates to using a navigation system interactively to provide alternate routes while driving.
In-vehicle navigation systems are available that provide end users (such as drivers of the vehicles in which the in-vehicle navigation systems are installed) with various navigating functions and features. For example, some in-vehicle navigation systems are able to determine an optimum route to travel by roads between locations in a geographic region. Using input firm the end user, and optionally from equipment that can determine one's physical location (such as a GPS system), a navigation system can examine various routes between two locations to determine an optimum route to travel from a starting location to a destination location in a geographic region. The navigation system may then provide the end user with information about the optimum route in the form of instructions that identify the driving maneuvers required to be taken by the end user to travel from the starting location to the destination location. The instructions may take the form of visual and/or audio instructions that are provided along the way as the end user is traveling the route. Some navigation systems are able to show detailed maps on computer displays outlining routes to destinations, the types of maneuvers to be taken at various locations along the routes, locations of certain types of features, and so on.
In order to provide these and other navigating functions, navigation systems use geographic data. The geographic data may be in the form of one or more databases that include data that represent physical features in a geographic region. The geographic database may include data representing the roads and intersections in a geographic region and also may include information relating to the represented roads and intersections in the geographic region, such as turn restrictions at intersections, the lengths of the represented roads and/or the distance between intersections along the represented roads, speed limits along the roads, the measured time of travel along the represented roads, street names of the various roads, address ranges along the roads, and so on.
Although navigation systems provide many important features, there continues to be room for improvements. One area in which there is room for improvement relates to using a navigation system to provide route guidance that takes into account driving or traffic conditions experienced by the vehicle driver. For example, a traffic condition may exist that affects how quickly a destination is reached. According to one example, the road ahead of the driver along the calculated route may be backed up with traffic congestion. This could be due to a large number of vehicles being on the roadway all at the same time, or perhaps to a traffic incident causing a temporary delay, or any number of other reasons. Under these circumstances, the calculated route may no longer be the quickest route to the destination, because information upon which the route was calculated may not match present conditions.
It is noted that some in-vehicle navigation systems have been proposed that permit the user to request calculation of an alternate route. In one such system, the user inputs a request for an alternate route calculation, and the system calculates the "next best" route to the destination from the vehicle's current location, and avoids either all or a portion of the original route. In another of such systems, the navigation system offers the user an option to elect an alternate route based upon whether the driver observes a condition at an upcoming intersection which, if true, would favor one maneuver at the intersection and, if false, would favor a different maneuver at the intersection.
It is further noted that some in-vehicle navigation systems have been proposed that obtain and use real-time traffic information. According to one type of proposed system, data about traffic congestion in a geographic area are collected by a traffic information service. The collected traffic data are filtered and processed. Then, the traffic information service broadcasts messages that contain information about the traffic congestion along roads in the geographic area. The in-vehicle navigation systems in the vehicles traveling in the geographic area include equipment that receive the messages. Programming in the in-vehicle navigation systems uses the information about traffic congestion when calculating optimal routes and when providing route guidance.
Although these types of proposed systems can be beneficial to vehicle users, these types of systems rely on the user to interact with the navigation system to cause it to calculate alternate routes or rely on the collection and broadcasting of traffic congestion information by a traffic information service. The driver may not always be in a position to observe the conditions required to instruct the navigation system to calculate an alternate route, or the driver simply may not want to interact with the navigation system in such fashion. Further, many geographic regions may not have a traffic information service that collects traffic data and broadcasts messages that can be used by in-vehicle navigation systems. Likewise, not all navigation systems may have receivers obtaining such traffic data, or may not have route calculation programs capable of accounting for such traffic data in calculating routes. Further still, even if a traffic information service is available in a geographic area and the navigation system can receive and utilize such traffic information, the traffic information service may collect and broadcast traffic congestion data about only certain roads (e.g., those that have the highest volume of traffic). If the driver of the vehicle with the in-vehicle navigation system is traveling on a road that is not covered by the traffic information service, he/she may not be able to obtain up-to-date traffic information. Even where the traffic information is available for all of the roads along the route, the broadcast traffic information may lag the real-time occurrence of certain types of incidents causing congestion that may favor the calculation of an alternate route.
Accordingly, there continues to be a need to provide alternate ways to provide navigation assistance to a vehicle driver using a navigation system.